Currently commercialized secondary batteries include nickel cadmium batteries, nickel metal hydride batteries, nickel zinc batteries, lithium secondary batteries, and the like. Among these secondary batteries, since lithium secondary batteries have advantages of being freely charged and discharged due to almost no memory effect as compared with nickel-based batteries and having extremely low self-discharge rate and high energy density, lithium secondary batteries are spotlighted.
Such lithium secondary batteries mainly include a lithium-based oxide and a carbon material as a positive electrode active material and a negative electrode active material, respectively. Lithium secondary batteries include an electrode assembly, in which a positive electrode plate and a negative electrode plate respectively coated with a positive electrode active material and an negative electrode active material are arranged with a separator therebetween, and an exterior, that is, a battery case, in which the electrode assembly and an electrolyte are sealed and received.
Generally, depending upon shapes of exteriors, lithium secondary batteries may be classified into can-type secondary batteries, in which an electrode assembly is embedded in a metal can, and pouch-type secondary batteries, in which an electrode assembly is embedded in a pouch of an aluminum laminate sheet.
Recently, secondary batteries are widely used in medium and large-sized devices such as automobiles or power storage devices as well as in small-sized devices such as portable electronic devices. When secondary batteries are used in medium and large-sized devices, a large number of secondary batteries are electrically connected to each other for improving capacity and output. In particular, pouch-type secondary batteries are frequently used in medium and large-sized devices due to merits thereof such as ease of stacking, light weight, and the like.
However, since pouch-type secondary batteries are generally packaged with a battery case of a laminate sheet of aluminum and polymer resin, pouch-type secondary batteries do not have high mechanical stiffness, and it is not easy for pouch-type secondary batteries to maintain a stacked state only by themselves. Thus, when a battery module including a large number of pouch-type secondary batteries is configured, a cartridge of a polymer material is frequently used to protect secondary batteries from external impact or the like, prevent movements of secondary batteries, and facilitate stacking.
A cartridge has the shape of a hollow quadrangular plate, and in this case, four sides of the cartridge are configured to surround an outer peripheral portion of a pouch-type secondary battery. In addition, when such a cartridge is used, a large number of cartridges are stacked to constitute a battery module, and secondary batteries may be located in an empty space inside the stacked cartridges.
In addition, when a battery module is configured using such a cartridge or the like, a fastening component for fixing between cartridges may be needed. That is, when a battery module is intended to be configured using a large number of secondary batteries and a large number of cartridges, there are needed fastening components, such as bolts or belts, which are capable of fixing the secondary batteries to the cartridges. Further, in this case, a cartridge or the like needs to include a configuration, for example, a hole or the like, to which a fastening component is coupled.
Therefore, according to a battery module configuration according to the related art, additional costs for cartridges, fastening components, or the like are required, and workability may be deteriorated due to no easy assembly. In addition, since a battery module has a large volume due to such cartridges, fastening components, or the like, there is a limit in reducing the size of a battery module.
In addition, a secondary battery may exhibit deteriorated performance when having a temperature higher than a proper temperature, and may be in danger of explosion or ignition in severe cases. In particular, when a battery module is configured by stacking a large number of pouch-type secondary batteries, since heat generated from a large number of secondary batteries in a narrow space is added up, the temperature of the battery module may be more quickly and severely increased. Further, a battery module included in an automotive battery pack may be frequently exposed to direct sunlight and may be placed under high temperature conditions such as summer or desert. Therefore, when a battery module is configured by using a large number of secondary batteries, it may be extremely important to secure a stable and efficient cooling capability.